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Hi folks,</div>
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Big upgrade process in the works and I had some questions. Our current infrastructure has 5 HA pairs of OSSs and arrays with an HA pair of management and metadata servers who also share an array, all running lustre 2.10.3. Pretty standard stuff. Our upgrade
plan is as follows:</div>
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1) Deploy a new HA pair of OSSs with arrays populated with OSTs that are twice the size of our originals.</div>
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2) Follow the process in section 14.9 of the lustre docs to drain all OSTs in one of existing the HA pairs' arrays</div>
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3) Repopulate the first old pair of deactivated and drained arrays with new larger drives</div>
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4) Upgrade the offline OSSs from 2.10.3 to 2.10.latest?</div>
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5) Return them to service</div>
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6) Repeat steps 2-4 for the other 4 old HA pairs of OSSs and OSTs</div>
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I'd expect this would be doable without downtime as we'd only be taking arrays offline that have no objects on them, and we've added new arrays and OSSs before with no issues. I have a few questions before we begin the process:</div>
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1) My interpretation of the docs is that we OK to install them with 2.10.6 (or 2.10.7, if it's out), as rolling upgrades withing X.Y are supported. Is that correct?</div>
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2) Until the whole process is complete, we'll have imbalanced OSTs. I know that's not ideal, but is it all that big an issue?</div>
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3) When draining the OSTs of files, section 14.9.3, point 2.a. states that the lfs find |lfs migrate can take multiple OSTs as args, but I thought it would be better to run one instance of that per OST and distribute them across multiple clients . Is that
reasonable (and faster)?</div>
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4) When the drives are replaced with bigger ones, can the original OST configuration files be restored to them as described in Docs section 14.9.5, or due the the size mismatch, will that be bad?</div>
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5) What questions should I be asking that I haven't thought of?</div>
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If that all goes well, and we did upgrade the OSSs to a newer 2.10.x, we'd follow it up with a migration of the MGT and MDT to one of the management servers, upgrade the other, fail them back, upgrade the second, and rebalance the MDT and MGT services back
across the two. We'd expect the usual pause in services as those migrate but other than that, fingers crossed, should all be good. Are we missing anything?</div>
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Cheers</div>
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Scott</div>
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